Re: question about disaster recovery ala virtualization
- From: "Greg D. Moore \(Strider\)" <mooregr_deleteth1s@xxxxxxxxxxx>
- Date: Fri, 24 Apr 2009 09:24:23 -0400
The biggest issue is write caching.
If the SAN tells SQL Server "data is written" but it's stored in cache on the SAN and the SAN dies and there's no battery backup, etc. then you risk data loss.
Any SAN worth its salt though will have battery backup, etc.
But if you eliminate the SAN as you have below, you're most likely fine. Still, make good backups and decide the most data you can risk losing.
But in many years of running SQL Server in all sorts of weird configurations, including some ones MS explicitely does NOT support, I've had VERY few issues with data loss.
--
Greg Moore
Ask me about lily, an RPI based CMC.
"aj" <ronald@xxxxxxxxxxxxx> wrote in message news:vZudncIvStP36G3UnZ2dnUVZ_j6dnZ2d@xxxxxxxxxxxxxxxx
I'm thinking about disaster recovery in the context of virtualization.
I have a virtual machine (call it VMWare ESX if it matters) on a host.
The VM is running SQL Server 2005. The SQL Server in the VM is using a
locally attached SAN for storage.
Lets say the motherboard on the host suddenly dies, while the SQL Server
VM is in the middle of a bunch of intensive writes to its files on the
SAN. However, the SAN itself (the disk subsystem) is just fine - only
the host, and the VM in it, go down.
Once the host is fixed, and the VM comes back, will the SQL Server
databases be OK? Or will there be data corruption? I'm thinking
that because SQL Server is ACID compliant, thing will be just fine.
Any inflight transactions will be rolled back as part of crash
recovery, and then things will be good. Am I correct?
Any thoughts appreciated..
aj
.
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